mouse-select

Select text, move borders, or run menu command.

M-<Left>

Press and release this mouse button to position point to wherever the
mouse cursor indicates, switching windows if needed. Hold down the
mouse button and drag to select and highlight text. Double-clicking
selects full words. (When a pop-up list of choices appears on the
screen, double-clicking on a choice selects it.) Shift-clicking
extends the current selection. Holding down the Alt key while
selecting produces a rectangle selection.

Drag selected text to move it someplace else. Hold down the Control
key to copy the text someplace else.

On scroll bars, this button scrolls the window. You can drag the
central scroll box up and down, click on the arrows at the top and
bottom of the scroll bar to scroll by lines, or click between the
arrows and the box to scroll by pages.

On other window borders and corners, dragging resizes windows. For
pop-up windows only, dragging the title bar moves the window.